Homopolar dynamoelectric machine



June 1953 J. v. CAPUTO ETAL HOMOPOLAR DYNAMOELECTRIC MACHINE Original Filed Oct. 16. 1947 fora! F/VZ'KY INVENTORAS. James V C'a vfa. {yummy (J Craz Patented June 2, 1953 2,640,942 I HOMOPOLAR. DYNAMOELECTRIC MACHINE James V. Caputo, Youngstown, Ohio, and Thomas J. Crawford, Berkley, Mich.; said Crawford assignor to said Caputo Original application October 16, 1947, Serial No.

780,170, now Patent No. 2,600,844, dated June 17, 1952. Divided and this application October 22, 1951, Serial No. 252,552

Claims. (01. 310 -178) The present invention relates to rotating electrical apparatus and more specifically to an electric dynamo which is adapted, among other uses, for the supplying of heavy pulses of current for relatively short intervals for a spot, projection, or flash-type electric resistance welding and is a division of our copending application, Serial No. 780,170, filed October 16, 1947, for Electrical Apparatus, now Patent No. 2,600,844, dated June 17,1952. Other features shown but not claimed 9 together upon a common shaft 8. The single herein are shown and claimed in our copendihg casing for the motor generator unit comprises application, Serial No. 230,152, filed June 6, 1951, a series of casing sections l0, l2, l4, and I6 which and application, Serial No. 252,551, filed October are suitably bolted together as by means of 22, 1951. 4 bolts I8.

The principal objects of the present invention The homopolar generator 2 comprises essenare: to provide an improved electrical current tially two complementary similar halves, one of generating apparatus of the character described; which is housed within the casing 10 and the to provide a new and improved energy storage other of which is housed within the casing 12 in and conversion apparatus; to provide an imgenerally the same manner as is disclosed and proved energy storage dynamoelectric machine claimed in J. V. Caputo Patent No. 2,005,609, having a flywheel for energy storage; to provide dated June 18, 1935. i such a machine which rotates about a vertical In the present construction a laminated core axis; to provide means for reducing the end 20 is provided on the shaft 8 for rotation therethrust against the bearings in such a vertically with and is aligned with a laminated field strucarranged electric machine; to provide a flux path ture 22 held rigid with the lower casing section for such a vertically arranged machine which l0. Inthe said Caputo patent, flux flows longiincludes at least a portion of the flywheel wheretudinally of the rotating shaft through a series by the attractive efiect of the flux will support of laminated core structures arranged 1ongitudithe flywheel; and generally to provide a new and nally of the shaft; howeve in e present app improved electric power-generatin apparatus cation, flux flows directly into the shaft and lonfor use in welding systems. gitudinally therethrough to the lower end por- Other and more detailed objects of the invention, some of the flux returning to the lower castion will appear in the following description and ing section 10 across an air gap 24 into an anin the appended claims. nular platelike portion 26 of the section 10 and In the accompanying drawings, which illushen pw rd hr h l s 8 f th casin sectrate preferred embodiments of the inv ntion tion [0 back to the laminated field structure 22 and throughout the several views of which correand across an a p 30 ack to the laminated spending reference characters are used to desigcore Othel f the flux passing W w d y nate corresponding parts: longitudinally through the shaft 8 flows out- Fig. 1 is a view in elevation of a motor-generaweirdly through a flywheel 32 Which is ey d by tor unit embodying the invention; and means of key 34 to the lower end of the shaft 8 Fig. 2 is a view of the lower portion of the throu an air p 36 to the annular platelike homopolar generator shown partly in centr l portion 26 and then returns to the laminated vertical section, the sections being taken along core in the manner above described in connection various radial lines to best illustrate the invenwith the flux which passes across the air gap 24. tion, By properly Droportioning the length of the It will be appreciated from a complete underair g p 24 a 3 the fl made t pass across standin of the present invention that the imthe gap 36 may be proportioned so that substanprovements thereof may be embodied in apparatially the entire Weight f e flywheel 32 y tug of idely varying capacities d i t d d be supported due to the attractive effect of the for widely different types of service; that in cerflux passing across the gap 36. If desired, the tain of their broader aspects many features of the g p 36 and. 24 may be so proportioned that not present complete system may be utilized inde- Only the Wei ht Of the flywheel 32 is supported by pendently of other features and that the present flu passing aCr the l 3 but also the W ht improvements maybe embodied in widely diiferf h her parts carried by the shaft 8 so that,

ing structural forms, The present disclosure, therefore, of a particular structural embodiment is to be regarded in an illustrative and not in a limiting sense.

The motor generator combination 1 comprises a homopolar generator portion 2, a motor driving portion 4, and an exciter 6 arranged in concentric fashion one above the other in a single casing and the rotors of which are all secured the end thrust during operation of the motor generator I may be relieved from the lower bearing 68 thereof. The lower bearing 38 for the shaft section 817 is preferably carried by a lower end bell 40 of the casing section it] which is secured thereto as by stud screws 42. Bolts 44 may extend through other apertures in the bell 46 whereby the motor generator I may be secured to a suitable footing 46. The end bell 40 is preferably made of non-magnetic material such as stainless steel or aluminum bronze and is electrically insulated from the bearing 38 by suitable insulation 4?. Similarly an upper end bell 49 of nonmagnetic material carries an upper bearing for the upper shaft section, the upper bearing being electrically insulated from the bell 49 by suitable insulation.

The upper portion of the homopolar generator 2 located within the casing section I2 is similar to that described and comprises an upper laminated core, a laminated upper field structure separated by an air gap so that flux from the upper field structure may flow across the gap through the upper laminated core upwardly through the shaft 8 radially outwardly across an air gap and back to the laminated upper field structure through the casing section 12. The laminated cores are provided with laminated inductors 48 which are spaced circumlerentially therearound and extend substantially parallel to the longitudinal axis of the rotating common shaft 8. As shown in said Caputo patent, the portion of the inductors 48 located in the core 20 are preferably slightly circumferentially offset from the portion of the inductors 48 carried by the laminated upper core to provide a diagonal connecting portion to permit limited longitudinal expansion and contraction of the inductors 48. The ends of the inductors 46 are each connected to radial flanges 52 of collector rings 54. The rings 54 are located concentric of the shaft 8 and held for rotation therewith between Wedge-shaped collars 55. Annular insulating members 53 insulate the collector ring 54 from the wedge-amped collars 56 whereby the ring 54 is electrically insulated from the shaft 8 and spaced therefrom to provide an annular coolant chamber 51. The collector ring 54 is located longitudinally along the shaft intermediate the core 20 and the annular platelike portion 26.

A similar ring is placed above the upper core and below an upper horizontal magnetic platelike number. Suitable field windings 6.0 are provided on the upper surface of the annular portion 26 for inducing a flow of flux across the air gaps 24, 30, and 36 in a path as above described.

The laminated field structures are provided with longitudinally extending conductor busses 64 which are parallel with the inductors 48 and are preferably equally spaced around the field structures. The sets of conductor busses carried by the field structures, unlike the inductors 48, are not interconnected together. All of the conductor busses 64 associated with the field structure 22 are electrically connected to an annular conducting ring 66 which serves as one output terminal of the homopolar generator 2. The conductor busses 64 associated with the upper field structure are likewise all connected together to a similar annular conducting ring 68 which serves as the other output terminal of the homopolar generator 2. The rings 66 and 68 are closely adjacent one another but are insulated from one another by an annular insulating ringlfl. The outwardly extending end portions of all of the 4 conductor busses 64 overlie the collector rings. To each of these overlying portions or the busses 64 is secured a brush holder 12 carrying one or more brushes which are resiliently urged against the associated collector rings.

The common shaft 6 of the motor generator I comprises a section 8a which is magnetic in character having secured thereto as by bolts a lower end section 8b of nonmagnetic material and having a similar end section also of nonmagnetic material at its upper end. The nonmagnetic end sections may, for example, be aluminum bronze or stainless steel. The rotating member of the driving motor 4 is suit-ably secured to rotate the common shaft 8, causing rotation of the rotating portions of the homopolar generator 2 and will also cause rotation of the rotor of the exciter 6. Preferably a three-phase alternating current motor is employed; however, any other type motor, whether alternating current or direct current, may be utilized. The exciter 8 may be any of the direct current generator types of properrating whereby a direct current voltage across its output terminals will be produced in accordance with its speed of rotation and the degree of energization of its exciting winding as will be more thoroughly brought out hereinafter.

The shaft 3 has a longitudinal central aperture or passageway 18 extending substantially the length of the shaft and a plurality of radially extending passageways leading from the aperture 78 to annular chambers 51 formed between the outer peripheral surface of the shaft 8 and the inner peripheral surface of the collector ring 54 and bound at its top and bottom by the wedge collar 56. The radial passageways 82 are spaced around the shaft 8 in such a manner that the static balance of the shaft 8 is preserved. Similar passageways interconnect the aperture 18 of the shaft 8 with a similar annular chamber intermediate shaft 8 and the upper collector rin located within the upper casing section l2.

It is believed that the remaining details of construction may best be understood by reference to a description of operation of the motor generator I which is as follows:

Upon energization of the motor 4 by suitable means well known in the art and not shown herein for simplicity, the shaft 8 will be rotated at motor speed. A suitable direct current enersizing circuit which includes the output terminals of the exciter 6 is connected to cause exciting current to flow through the field windings 60 of the homopolar generator 2. With the field windings 60 excited, flux will flow through the paths in the generator hereinbefore described and across the air gaps 24, 30 and 36 and air gaps similar to gaps 24 and 36 in the upper portion of the homopolar generator 2. This flux passes substantially radially across the gaps 30 and through the laminated cores 20 downwardly and upwardly through the shaft section Go. It should be noted that since the end bells 40 and 49 and lower and upper shaft sections are of nonmagnetic material and will not conduct flux, the flux path will not extend through the bearings. Since the bearings are completely insulated from the end bells 40 and 48 no current will pass therethrough due to any possible unbalance in voltage induced due to the cutting of the flux by the shaft section 8a.

As the shaft section 80 and the cor 20a rotate, this fiux will be cut by the 48, causing a voltage to be induced therein. si c the direction of cutting of the flux by the inductors 48 associated with the core 20 and the inductors 48 associated with the upper core is in the same direction, the voltages induced by the cuttings of the flux passing across the gaps 30 will be additive. The upper collecting ring will be of one polarity and the lower collector ring 54 will be of the opposite polarity. The collector rings are electrically connected by means of the associated brushes to the respective sets of conductor busses B4 and therethrough to the corn ducting rings 66 and 68 which form the output terminals of the homopolar generator 2.

When the welding current load. circuit con nected between rings 66 and 68 is closed, whereby welding current is supplied thereto, the power required to effect the welds is usually somewhat greater than the power which may be transferred by the driving motor 4 to the shaft 8 so that the shaft 8 tends to reduce somewhat in speed. Due to the presence, however, of the flywheel 32 and the kinetic energy thereof, the shaft 8 will tend to rotate at a substantially constant speed and supply additional energy to the generator 2.

As the generator 2 is so used, heat due to the passage of current through the collector rings 54 and 54a will be generated therein, causing coolant to circulate through the annular chambers 51, which flow of coolant through chambers 51 will be somewhat proportional to the current output of the generator 2 whereby the rings 54 will be maintained with the normal temperature op erating limit.

What is claimed and is desired to be secured by United States Letters Patent is as follows:

1. In an electric power-converting apparatus, a homopolar generator having a rotor arranged to rotate about a vertical axis and including a flux circuit having first and second portions arranged in parallel circuit with each other, said first circuit portion having a substantially vertically extending gap, a flywheel arranged to rotate with said generator rotor, said second circuit portion including said flywheel and a horizontally extending gap immediately above said flywheel whereby the end thrust of said rotor is at least partially carried by the flux flowing through said flywheel.

2. A vertically arranged homopolar generator comprising a stationary flux-conducting member and a rotatable flux-conducting member providing a closed flux path, means providing a first flux path portion including a vertically extending non-magnetic portion, a flux-conducting member carried by said rotatable flux-conducting member and arranged in underlying relationship with said stationary fiux member to provide a second path portion in parallel circuit with said first path portion, said second path portion including a vertical gap, the reluctance of said second flux path portion from said stationary flux member through said last-named flux-conducting member across said gap to said rotating flux-conducting member being so related to the reluctance of said first path portion that the flux flowing through said last-named flux-conducting member and across said gap will at least partially support the weight of said rotatable flux-conducting member.

3. A vertically arranged homopolar generator comprising a stator and a rotor, means providing a closed flux path through said stator and said rotor and including a flux circuit having first and second flux path portions to provide parallel flux circuit portions in said fiuX circuit, means providing a substantially vertical gap in said first flux path portion, a stationary flux conducting member in said flux circuit, a flux-conducting metallic member rotatable with said rotor, said member underlying said stationary flux conducting member and spaced from said stationary member to provide a substantially horizontal gap across which flux may flow, said gaps being so proportioned relative to each other as to permit sufficient flux to flow between said horizontal portion and said member to at least partially support the weight of said member and said rotor.

4. A vertically arranged homopolar generator comprising a supporting structure having a transversely extending wall adjacent its lower end portion, said wall having a central aperture therethrough and a lower surface, a vertically extending rotor shaft in said structure and extending through said aperture, said shaft being of lesser cross-sectional area at its portion within said aperture than the cross-sectional area of said aperture to provide a substantially vertical gap, a flywheel carried by said shaft below said wall and having an upper surface spaced from said wall lower surface to provide a substantially horizontal gap, means operable to set up a flow of flux through said wall and across said first and second-named gaps into said shaft, said gaps being so interproportioned as to provide sufficient flux flow across said second-named gap to said flywheel to support at least partially the weight of said shaft and said flywheel.

5. A vertically arranged homopolar generator having a supporting structure including vertically spaced bearings, a shaft carried by and rotatable in said bearings, a laminated rotor carried on said shaft, a laminated field carried by said structure in radial alignment with said rotor, said rotor and said field and said structure and said shaft co-operating to provide a closed flux path, means providing a substantially vertical air gap in said flux path between said structure and said shaft, a flywheel carried by said shaft and having a portion extending across said air gap adjacent a portion of said flux path in the stationary parts of the generator, said adjacent portion of said flywheel being slightly spaced from said flux path portion to provide a substantially horizontal air gap, said air gaps being so proportioned relative to each other that a portion of the flux flows across said last-named gap into said flywheel and therethrough into said shaft whereby said flywheel is at least partially supported thereby to decrease the end thrust on said bearings.

JAMES V. CAPUTO. THOMAS J. CRAWFORD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 371,199 Kimball et a1 Oct. 11, 1887 457,902 Kintner Aug. 18, 1891 804,440 Steinmetz Nov. 14, 1905 876,943 Canfleld Jan. 21, 1908 

